The invention concerns a rammer for artillery shells with a carriage behind the gun's tube that supports a tray in alignment with the powder chamber, that has a mechanism at the rear to intercept the shell, that travels on slides along a track paralleling the axis of the tube, that is coupled to a piston-and-cylinder drive mechanism to accelerate toward the tube, and that has a braking mechanism to brake it at a prescribed distance from the rear end of the tube.
In loading artillery shells, the projectile, which weighs 50 kg or more, must be thrust far enough into the tube at least 1.5 m/sec to force the soft-metal guide ring on the shell into the conical section of the powder chamber. The force must be powerful enough to prevent the shell from falling out subject to its own weight even when the tube is at maximum elevation and simultaneously to weal off the front of the powder chamber.
Since manual ramming by the gun crew takes time and is very tiring, mechanical rammers of various types have been developed.
Especially significant are what are called free-flight rammers that operate on the principle of accelerating the projectile to such an extent while it is still outside the gun that, once it has left the accelerating system, its momentum will carry it forward unsupported. A free-flight rammer of this type is described in U.S. Pat. No. 4,754,688 for example.
Also known is a free-flight rammer with the aforesaid characteristics wherein the shell resting on the carriage is accelerated along with the carriage, which is braked once the requisite ramming speed has been attained. The shell then flies on through the breech plate and powder chamber and rams into the grooves in the tube. The carriage is powered with a pneumatic or hydraulic piston-and-cylinder drive mechanism.
Two problems occur with free-flight rammers of this type. First, the carriage-plus-shell system must be powerfully accelerated to attain the maximum ramming speed. Second, the direction that the shell travels in when the carriage is braked must be very precisely aligned with the axis of the tube so that it will not scrape against the walls of the breech plate and powder chamber as it travels through them, which would damage either the shell or the gun. Since the tolerance is usually only a few millimeters, care must be taken to ensure that no interfering forces occur when the carriage is braked that would add moments to the rammer and deflect the shell from its alignment with the axis of the tube.